Known oil supplying apparatuses for automobiles, which feed working oil applied for lubricating an engine to each portion in the engine, are configured to have a structure by which output volume of the working oil is variable and which appropriately regulates discharge pressure of the working oil in response to a rotation speed of the engine.
For example, a known oil supplying apparatus described in Japanese Patent JP2005-140022A, which is hereby incorporated by reference herein in its entirety. The oil supplying apparatus described JP2005-140022A includes an inlet port which sucks working oil in response to a rotation of a rotor driving synchronously with a crankshaft, a first outlet port and a second outlet port which discharge the working oil in response to the rotation of the rotor. The oil supplying apparatus further includes a first oil path which feeds the working oil at least from the first outlet port to a portion to be supplied with working oil, a second oil path which feeds the working oil from the second outlet port to the first oil path, and a relief oil path which returns the working oil from a hydraulic pressure control valve, which includes a valve body operating in response to a hydraulic pressure of the working oil in the first oil path, to at least one of the inlet port and an oil pan.
With the construction of the known oil supplying apparatus described in JP2005-140022A, the valve body includes a first valve chamber and a second valve chamber. When the level of the hydraulic pressure of the working oil in the first oil path is within a predetermined range, the working oil from the second outlet port is supplied to the first oil path via the first valve chamber. And the working oil from the second outlet port is supplied to the first oil path via second valve chamber when the oil pressure of the working oil in the first oil path is greater than the predetermined range.
When the hydraulic pressure of the working oil in the first oil path is within the predetermined range and the oil supplying apparatus is structured so that the working oil from the second outlet port is supplied to the first oil path via the first valve chamber, the volume of supplied working oil to the first oil path, in this case, is a total of the output volume from the first outlet port and the output volume from the second outlet port.
In the case where the required level of the hydraulic pressure is ensured only by the working oil from the first outlet port because of an increase of a rotation speed of the rotor and a rotation speed of an internal combustion engine, it is not necessary to merge the working oil from the first oil path and the working oil from the second oil path. In those circumstances, the excessive working oil in the second oil path is returned to the relief oil path without being supplied to the first oil path.
On the other hand, when a rotation speed of the rotor is within a high-speed range, a supply of the large volume of the working oil may be required depending on types of a portion to be supplied with the working oil. Therefore, according to the known oil supplying apparatus described in JP2005-140022A, when the hydraulic pressure of the working oil to the first oil path is greater than the predetermined range, the working oil from the second outlet port is supplied to the first oil path via the second valve chamber. In those circumstances, even after the working oil is assumed to be supplied to the first oil path only from the first outlet port once, a total of the output volume of the working oil from the first outlet port and the working oil of the output volume of the second outlet port is re-supplied to the first oil path.
Accordingly, with the construction of the known oil supplying apparatus described in JP2005-140022A, because the volume of the working oil to be supplied can be increased even when the rotation speed of the rotor is within the high-speed range, necessary oil volume to be supplied to the portion to be supplied with the working oil is securely ensured.
Meanwhile, with the construction of the known oil supplying apparatus described in JP2005-140022A, the total volume of the working oil from the second outlet port flows into the first outlet port via the first valve chamber and the second valve chamber of the valve body provided at the oil pressure control valve. In this case, in order to reduce pressure loss, dimensions of the valve body and the oil pressure control valve are increased. However, when mounting the oil supplying apparatus on the engine, it is preferable to downsize the oil supplying apparatus.
A need thus exists for an oil supplying apparatus for an engine which is not susceptible to the drawbacks mentioned above.